Chocolate-Coconut Cubes

Shake can of coconut milk. Open, pour into a bowl and whisk until smooth. Divide in half; add cocoa powder and sugar to one half and whisk again. Fill an ice tray with chocolate-coconut milk, about 1 tablespoon per cube, and freeze until solid, 1 to 2 hours.

Divide reserved plain coconut milk among cubes and refreeze until solid. (Change the patterns of stripes as desired.) Divide cubes among four glasses and add chilled coffee.